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Biomedical subjects

K Hermann

Publications and source records attributed to K Hermann.

At least 73 records · Page 4Linked to original sources
PubMed1987

Presence of renin in primary neuronal and glial cells from rat brain.

Immunocytochemical and biochemical techniques have been utilized in the present study to characterize renin in brain cell cultures. With the use of renin-specific antibody, positive renin staining was seen in neuronal and in astrocytic glial cells using the peroxidase-antiperoxidase method. Renin concentration was pH-dependent with highest concentrations at 5.5, decreasing from pH 6.0 to 6.5. At pH 7.4 no renin was detectable in either glial or neuronal cells. The contribution of cathepsin D to the measured renin was about 10% at pH 5.5; 7% at pH 6.0 and 3% at pH 6.5. Comparison of glial with neuronal cells from WKY rats revealed significantly elevated renin at pH 5.5 in glial cells. No difference was seen between glial and neuronal renin levels in WKY rats at pH 6.0 and 6.5. At pH 5.5 and 6.0 renin was significantly increased in neuronal cells of SHR compared to WKY, whereas at pH 6.5 no difference was observed. The renin concentration in cells kept for 2 days in serum-free medium did not differ from those measured in cells kept in serum-containing medium. The generated peptide was identified as [Ile5]Angiotensin I on reversed-phase HPLC.

Angiotensin I↗
PubMed1987

[Value and rank of diagnostic laboratory parameters in cardiovascular diseases. Results of multivariant and discriminant analyses of the Berlin EBMO-Cor population study].

Based on present clinical-chemical parameters a representative population were studied; importance and order of rank of 10 data chosen from a total data pool are determined by means of multivariant and discriminant analysis. As a result the validity of characters with and without apriori probabilities for 5 pairs of classes (persons suffering from a heart disease in comparison to healthy persons divided in sexes and overall, as well as examination of separate sexes for healthy persons and those suffering from a heart disease) are examined (alpha less than or equal to 0.05). This calculation tested the importance of the parameters hemoglobin and creatinine in being different in males and females. To diagnose persons suffering from a heart disease (X-ray-morphologically defined suspects of heart and vessel diseases) from healthy persons, the optimized number of characteristics were determined in cholesterol, erythrocyte sedimentation rate, ASAT, blood glucose (independent of sex). By means of these results it is possible to identify persons suffering from a heart disease from healthy persons and to call for illustrative laboratory examinations using already mentioned parameters and the function of discriminance W = p sigma i = 1 ai X Xi. The determination of sensitivity and specification yielded a value of up to 98 per cent resp. 94 per cent depending on whether with or without apriori probabilities. This enables use to be modified to suit different purposes.

Adolescent↗
PubMed1986

Kinins in cerebrospinal fluid: reduced concentration in spontaneously hypertensive rats.

Rat cerebrospinal fluid contains peptides which displace radiolabeled bradykinin from its specific antibodies. Two peptides which showed the same retention time as kallidin and bradykinin in a reverse phase high pressure liquid chromatography system were detected in cerebrospinal fluid of rats. The concentration of radioimmunologically detected kinins in the cerebrospinal fluid of spontaneously hypertensive rats of the Okamoto strain was lower than that of the Wistar Kyoto control rats.

Animals↗
PubMed1986

Isolation and purification of angiotensin II using affinity and high-pressure liquid chromatography.

Peptides have been found in a variety of tissues including brain. To purify the peptide angiotensin II, a three-step method for the isolation and purification has been developed using extraction, affinity chromatography, and high-pressure liquid chromatography. Angiotensin II antiserum purified by affinity chromatography was covalently coupled to Affi-gel 10 (Affi-gel 10-AB). The efficiency and usefulness of this column for the purification of angiotensin II from biological sources were tested with 125I- and 3H-labeled (Ile5)-angiotensin II added to rat brains prior to extraction. After extraction, the recoveries for both peptides were 74 and 75%, respectively. Recovery after the purification on Affi-gel 10-AB was 84 and 82%. Thirty-two percent of the radioactivity was not retained and 50% of the radioactivity could be eluted with 0.1 M Na citrate buffer containing 1 M NaCl using a stepwise pH gradient. Characterization by HPLC of the unretained radioactivity from the Affi-gel 10-AB column showed one peak for [125I]angiotensin II, coeluting with the [125I]angiotensin II standard and two minor peaks. Only 30% of unretained [3H]angiotensin II could be identified as intact [3H]angiotensin II on HPLC. Both [125I]angiotensin II and [3H]angiotensin II elutable at pH 5.0 and 4.0 on Affi-gel 10-AB could be demonstrated as highly purified [125I]angiotensin II and [3H]angiotensin II on HPLC with a purity of more than 90%. On HPLC, the recovery was 81% for [125I]angiotensin II and 99% for [3H]angiotensin II. The recovery for the entire three-step procedure was about 60%. The loading capacity of the Affi-gel 10-AB column for (Ile5)-angiotensin II was 550 ng.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1984

Combined high-performance liquid chromatography-radioimmunoassay for the characterization and quantitative measurement of neuropeptides.

A method for the extraction, separation, characterization and quantitation of angiotensins, opioid peptides and several other neuropeptides in biological samples is described. Gradient elution in different reversed-phase high-performance liquid chromatographic systems gives high resolution with constant recoveries between 60 and 70%, allows UV detection at 220 nm and is compatible with radioimmunoassay. The method is highly reproducible and applicable to the characterization and quantitative measurement of peptides in the femtomolar range. The practicability of the method is demonstrated for angiotensin peptides in plasma, brain and peripheral organs, as well as for opioid peptides in the heart.

Angiotensin I↗
PubMed1984

Angiotensin biosynthesis and concentrations in brain of normotensive and hypertensive rats.

We report here on the extraction and characterization of angiotensin I (ANG I) and angiotensin II (ANG II) from the brain of rats. High pressure liquid chromatography (HPLC) with different mobile phases combined with specific radioimmunoassays (RIA) proved to be a powerful tool for peptide characterization in biological samples; (Ile5)-ANG I, (Ile5)-ANG II and (Ile5)-ANG III could clearly be identified in cerebrospinal fluid (CSF), incubated in vivo and in vitro with renin, in total brain extracts, as well as in hypothalamus (HT), medulla oblongata (MO), cerebellum (CER) and cortex (CO). Angiotensin cleaved from CSF angiotensinogen and angiotensin extracted from brain showed retention times identical to those of plasma angiotensin and synthetic standard peptides, indicating that their amino acid sequence is probably identical. ANG I and ANG II were highest in the HT and lowest in the CO. Following bilateral nephrectomy (NX) both ANG I and ANG II persisted at control levels. Young 10 week old spontaneously hypertensive rats (SHRSP) showed significantly lower ANG I and ANG II concentrations in the HT compared with Wistar Kyoto rats (WKY). Intracerebroventricular (i.c.v.) administration of the converting enzyme inhibitor captopril caused a significant increase in ANG 1 in nephrectomized SHRSP but not in WKY. These differences were not found in 40 week old SHRSP. The data show that ANG I and ANG II are synthetized in the brain of rats. The lower concentrations and the enhanced accumulation of ANG I after converting enzyme blockade in nephrectomized young SHRSP indicate an increased turnover of angiotensin in hypertensive rats.

Angiotensin I↗
PubMed1983

Angiotensin synthesis in the brain and increased turnover in hypertensive rats.

The missing link in the evidence for an active endogenous renin angiotensin system in the brain has been the demonstration of local angiotensin synthesis in the central nervous system in vivo. In this report the extraction and characterization of angiotensin I and angiotensin II from the brain of rats is described. The accumulation of angiotensin I was enhanced in hypertensive rats when the conversion to angiotensin II was blocked in vivo by the converting enzyme inhibitor captopril.

Angiotensin I↗
PubMed1983

N-terminal peptide of pro-opiomelanocortin in human amniotic fluid.

N-terminal peptide of pro-opiomelanocortin (N-POMC) was measured in the human amniotic fluid. At the gestational age of 16 to 20 weeks, the radioimmunoassay with three different antibodies demonstrated the respective values of 2.39 +/- 0.78, 4.69 +/- 2.27, and 5.92 +/- 2.66 ng/ml. These values are approximately 10 times higher than the measurements in the plasma of women at the corresponding gestational period. The amniotic fluid collected during the delivery had significantly lower concentrations of N-POMC than the amniotic fluid at 16 to 20 weeks' gestation. However, the plasma values of N-POMC had increased approximately three times when measured at delivery and compared with the plasma values at 16 to 20 weeks' gestation. Adrenocorticotropic hormone, measured simultaneously with N-POMC in some of the samples, showed changes similar to those in N-POMC. The N-POMC immunoreactivity from the amniotic fluid has the same retention time on reversed-phase high-performance liquid chromatographic separation as the peptide purified from the human pituitary gland, thus indicating the identity of both peptides.

Adrenocorticotropic Hormone↗
PubMed1983

Effects of lesions in the paraventricular nucleus of the hypothalamus on vasopressin and oxytocin contents in brainstem and spinal cord of rat.

The effects of lesions of the paraventricular nucleus in rat hypothalamus (PVN) on the vasopressin (AVP) and oxytocin (OT) contents of the brainstem and spinal cord, as measured by radioimmunoassay, were studied. AVP decreased by 50% and 80% in brainstem and spinal cord of lesioned animals, whereas OT disappeared almost completely. Therefore, in contrast to OT, the PVN is not the only site of origin of AVP-containing nerve fibers projecting to the brainstem.

Animals↗
PubMed1983

Evidence for the presence of enkephalins in the heart.

Extracts of guinea pig hearts were subjected to high performance liquid chromatography (HPLC) and the eluted fractions monitored by radioimmunoassays (RIA) for their content of leucine5-enkephalin (Leu-ENK) and methionine5 enkephalin (Met-ENK). Distinct peaks of both Leu-ENK and Met-ENK immunoreactivity were found corresponding to the position of synthetic Leu-ENK and Met-ENK respectively. The ratio of Leu-ENK to Met-ENK content was about 1:4. Chemical sympathectomy with 5-hydroxydopamine (6-OH-DA) produced a dramatic fall in noradrenaline content of the heart by more than 99%, whereas the concentration in Leu-ENK was reduced by only 70%. The Leu-ENK content of the adrenal glands was not affected by this treatment. These observations point to an enkephalinergic innervation of the heart which appears to be mainly of sympathetic origin. The results suggest the participation of enkephalins in cardiac reflex mechanisms.

Animals↗
PubMed1983

Oxytocin unlike vasopressin is a stress hormone in the rat.

The functions of oxytocin in the female are thought to be confined to the processes of milk ejection and parturition. In this study the role of oxytocin in the body's response to stressful stimuli has been examined. Physical immobilization of rats and forced swimming caused large increases in the secretion of the hormone, whereas vasopressin levels remained unchanged. These findings classify oxytocin, in contrast to vasopressin, as a so-called 'stress hormone' and suggest its importance in processes other than those related to reproduction.

Animals↗